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ARRL Propagation Bulletin ARLP003 (2019)

ARLP003 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 3  ARLP003
From Tad Cook, K7RA
Seattle, WA  January 18, 2019
To all radio amateurs 

ARLP003 Propagation de K7RA

No sunspots seen since January 6, so average daily sunspot numbers
declined from 7.7 to 0 for the current reporting week, January
10-16. Average daily solar flux dropped from 71.6 to 69.4 over the
same period. Average daily planetary A index went from 7.4 to 4.9,
and average mid-latitude A index went from 6.1 to 4.

Predicted solar flux for the next 45 days is 70 on January 18-20, 72
on January 21-24, 71 on January 25 through February 1, 70 on
February 2-4, 69 on February 5-13, 70 on February 14-15, 71 on
February 16-28, and 70 on March 1-3.

Predicted planetary A index is 5 on January 18-22, then 8, 20, 12
and 8 on January 23-26, 5 on January 27-30, then 10, 15, 12 and 8 on
January 31 through February 3, 5 on February 4-10, then 12 and 10 on
February 11-12, 5 on February 13-19, then 18, 10 and 8 on February
20-22, 5 on February 23-26, then 12, 18, 15, 10 and 5 on February 27
through March 3.

Predicted smoothed sunspot number for January 2019 is 9. This
predicted smoothed sunspot number is what you want to use this month
with propagation prediction programs such as W6ELprop, rather than
daily sunspot numbers. K9LA explains:

"Why should we use the smoothed sunspot number (or smoothed solar
flux) and not the daily solar flux? To develop the model of the
ionosphere for our propagation predictions, solar data was compared
to ionosphere data. The best correlation was between the smoothed
sunspot number (or smoothed solar flux) and monthly median
ionospheric parameters. Thus the model was designed to take a
smoothed solar index. The 'monthly median' aspect means that our
predictions are statistical in nature."

No geomagnetic forecast from OK1HH again this week, until he resumes
his predictions on January 31. But we have a similar prediction from
Tomas Bayer of the Institute of Geophysics at the Department of
Geomagnetism at Budkov observatory in Prague.

"Geomagnetic activity forecast for the period January 18-24, 2019:

"Quiet: Jan 18-23
Unsettled: Jan 19-21
Active: Jan 24-25
Minor storm: possible Jan 24

"Geomagnetic activity summary:

"We expect an active episode at the end of the forecast period,
January 24-25. This episode can peak as a minor storm event although
it need not exceed local K-index of 4. Nevertheless, a minor storm
event is possible. Until this event, we expect at most quiet to
unsettled conditions, from Friday, January 18 until Wednesday,
January 23, we expect quiet conditions only with an isolated
unsettled event."

The latest from Dr. Tamitha Skov:

"Dear Tad,

"I just returned from the American Meteorological Society (AMS)
meeting held in Phoenix, Arizona and the air feels electric. Even
though the government absences were sorely noted (#WeMissNOAA
hashtags were everywhere for example), the meeting was still a buzz
of activity. Strangely enough, the cancellations caused by the
furlough actually helped the Space Weather Conference, as it brought
many terrestrial meteorologists out of their niche looking for
interesting talks to see. Between the Parker Solar Probe and the
recently declassified military report on the 1972 super solar storm,
we definitely had Space Weather stories to tell.  But what stuck out
even more than these stories were the set of talks Mike Cook and I
did on this Space Weather community. It was all about you and how
you have trained us scientists in the art of Space Weather

"Luckily, I've now learned to come to meetings equipped with
multiple cameras. If you have taught me anything on this journey,
it's that you want to share in it with me -- and over the next few
months, I plan to share it all. I will be releasing interviews and
chats, interpretations of talks, 360 degree videos, and more. Some
highlights will be included in my forecast videos (like the Parker
Solar Probe interview included this week). However, much more will
be found on Patreon, where I can freely post videos without worrying
about time limitations. I can also post extra information, images,
and charts that can serve as additional resources. This is such an
exciting time!

"In the forecast this week, Space Weather may be settling down, but
the excitement surely hasn't as we dive into the promising new era
of the Parker Solar Probe. During his cameo, Nour Raouafi, the
Project Scientist for the mission, says what the Probe is observing
will forever change how we look at the Sun, its corona, and the
solar wind. Although the data hasn't been made public yet (in fact,
I was prohibited from taking pictures during Nour's talk), what we
have seen thus far is simply stunning. It could fundamentally change
our entire picture of how Space Weather reaches Earth.

"Cheers, Tamitha."

David Moore and Max White, M0VNG passed along this link about a
comprehensive model of the life of a solar flare:

If you would like to make a comment or have a tip for our readers,
email the author at, .

For more information concerning radio propagation, see the ARRL
Technical Information Service web page at, For an explanation of
numbers used in this bulletin, see

An archive of past propagation bulletins is at More good
information and tutorials on propagation are at

Monthly propagation charts between four USA regions and twelve
overseas locations are at

Instructions for starting or ending email distribution of ARRL
bulletins are at

Sunspot numbers for January 10 through 16, 2019 were 0, 0, 0, 0, 0,
0, and 0, with a mean of 0. 10.7 cm flux was 70.1, 68.1, 69.6, 68.9,
70, 69.5, and 69.7, with a mean of 69.4. Estimated planetary A
indices were 4, 7, 3, 3, 6, 5, and 6, with a mean of 4.9. Estimated
mid-latitude A indices were 3, 5, 2, 3, 6, 4, and 5, with a mean of


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